Weird Error when it comes to any video

Hey I recently upgraded to a shuttle barebone which i had quite a few problems with but in the end after several windows XP repairs and reinstalls i got it to work to a standard i am happy with. However, everytime I go to play any video in WMP or in Quicktime or realplayer the player I am using at the time causes the CPU usage to jump to 100% and locks up the system. It then takes me 5 minutes to override the program and shut it down in task manager processes table. This occurs while I use firefox as well when i try to load a video say on Cnet.com. It is quite annoying and i havent run into this kind of problem before. Does anyone know what the problem may be? thanks in advance